Abstract We hypothesized that seeds of the central Asian cold desert shrub Zygophyllum xanthoxylon exhibit dormancy cycling in nature, which would help ensure that germination occurs at a favorable time for seedling survival. Fresh mature fruits of Z. xanthoxylon were placed on the soil surface and buried at a depth of 3–5 cm in soil in a natural habitat in August 2015. At regular intervals until July 2017, fruits/seeds were taken to the laboratory and evaluated for viability and germination. Fresh seeds in fruits germinated to 22–62% over a range of temperatures. After 6 weeks in the field, seeds on the surface germinated to 72–99% and those in soil to 70–100%. From 12 to 98 weeks, seeds on and in soil germinated to 72–100% at low (15/5 and 20/10 °C) temperatures, but germination at high (25/25 and 30/15 °C) temperatures was higher in summer than in spring. Seeds in fruits on the soil surface had higher germination percentages than those in the soil, especially at high temperatures. Although about half the seeds were dormant at maturity, they became nondormant in the field during summer. There was a decrease in ability to germinate at high temperatures in spring, especially for seeds in buried fruits, which indicates conditional dormancy/nondormancy cycling. Lack of germination at high temperatures in spring would help delay germination until the onset of the summer rainy season in the desert. Burial of fruits in the soil enhances the formation of a short-lived persistent seed bank.

中文翻译：

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荒漠冷漠灌木叶黄木果实中种子的季节性萌发响应

摘要 我们假设中亚寒冷沙漠灌木 Zygophyllum xanthoxylon 的种子在自然界中表现出休眠循环，这将有助于确保萌发发生在有利于幼苗存活的时间。2015 年 8 月，将新鲜成熟的 Z. xanthoxylon 果实置于土壤表面，埋入自然栖息地土壤中 3-5 cm 的深度。直到 2017 年 7 月，定期将果实/种子带到实验室进行评估为生存力和发芽。水果中的新鲜种子在一定温度范围内发芽率高达 22-62%。在田间种植 6 周后，地表种子发芽率为 72-99%，土壤中的种子发芽率为 70-100%。从 12 到 98 周，土壤上和土壤中的种子在低温（15/5 和 20/10 °C）下发芽到 72–100%，但在高温（25/25 和 30/15 °C）下，夏季发芽率高于春季。土壤表面果实种子的发芽率高于土壤种子，特别是在高温下。尽管大约一半的种子在成熟时处于休眠状态，但它们在夏季在田间处于非休眠状态。春季高温下发芽能力下降，特别是埋藏果实中的种子，这表明有条件的休眠/非休眠循环。春季高温下发芽不足将有助于延迟发芽，直到沙漠中夏季雨季开始。将果实埋在土壤中可促进短期持久种子库的形成。尤其是在高温下。尽管大约一半的种子在成熟时处于休眠状态，但它们在夏季在田间处于非休眠状态。春季高温下发芽能力下降，特别是埋藏果实中的种子，这表明有条件的休眠/非休眠循环。春季高温下发芽不足将有助于延迟发芽，直到沙漠中夏季雨季开始。将果实埋在土壤中可促进短期持久种子库的形成。尤其是在高温下。尽管大约一半的种子在成熟时处于休眠状态，但它们在夏季在田间处于非休眠状态。春季高温下发芽能力下降，特别是埋藏果实中的种子，这表明有条件的休眠/非休眠循环。春季高温下发芽不足将有助于延迟发芽，直到沙漠中夏季雨季开始。将果实埋在土壤中可促进短期持久种子库的形成。春季高温下发芽不足将有助于延迟发芽，直到沙漠中夏季雨季开始。将果实埋在土壤中可促进短期持久种子库的形成。春季高温下发芽不足将有助于延迟发芽，直到沙漠中夏季雨季开始。将果实埋在土壤中可促进短期持久种子库的形成。